About two years I literally inherited a 65G tank populated with 4 Red Tail sharks, 2 Pleco's a Cory and what I can only identify as a Paroon or ID shark. Had I not taken this tank the owner's wife would have released all the fish in a local lake.

I've had essentially no problems with the tank despite the fact that the Plecos are in excess of 9" and the paroon or ID has exceeded 1 foot. The tank has become quite stressful for me as the larger fish is very easily startled and will have fits where it hits objects or the glass so hard I fear it will take out the side of the tank. Regular maintenance has become something I dread.

Presently the tank has a Fluval 306 and a 305 as well as UV filtration due to the size of the fish. A couple days ago I did a 15% water change and the larger fish went absolutely berserk and would not settle down, I turned off the lights in the tank in the hopes that the fish would settle down, but for the remainder of the evening I could hear it smashing against the sides of the tank. The following morning I checked on the tank and to my surprise I discovered 3 dead Read Tails and a dead Cory. The remaining Red Tail had lost it's colour and was floating vertically in the tank. Long story short, the last Red Tail, appears to have recovered, but I wonder if the agitation of the larger fish could have attributed to the death of my other fish. The water in the change was fine as I used it at the same time in a 40G tank with no ill effects.

Sorry for the long post but any help would be appreciated.

Thanks

Agent13

02-13-2014 02:10 PM

I'd put money on the shark freaking out caused this . Now those two species you've said you think it may be actually look pretty different. Does yours have a long dorsal fin? Either way your going to need to get a tank sooo massive that I can't even put a gallon size on it or you're going to need to find an aquarium somewhere that is willing to take it . Neither of these fish are appropriate for home aquariums . You're looking at 5-10ft with the paroon shark and about 3feet with the ID shark. People think they are smaller because they die premature deaths long before they are done growing . The freaking out and jumpiness sounds like an ID shark. Even if you did get a large tank .. The id shark is a schooling fish.. I don't see it possible to keep happy or alive much longer . I apologize to be the bearer of bad news . Also if those are common plecos .. You'll need a MUCH bigger tank if you want to keep them as well.

Do you have any test results? From the sounds of it you're afraid to do water changes often. My guess right now is going to be old tank syndrome for a bunch of large fish and too little water changes.

You did a good thing by stopping the fishes' release, but I have to tell you that old owner had some really horrible stocking, particularly the paroon shark with its potential to reach 10 ft in the wild.

Agent13

02-13-2014 02:32 PM

Quote:

Originally Posted by BWG
(Post 3917114)

First off, I'm sorry for your losses.

Do you have any test results? From the sounds of it you're afraid to do water changes often. My guess right now is going to be old tank syndrome for a bunch of large fish and too little water changes.

.

Oops.. Good point. I got stuck on the shark and forgot to notice the lack of maintenance .

Welcome to the forum, TFoster - I'm sorry for your losses T___T
It looks like there may be a combination of things at work here. . .
would you mind sharing your maintenance routine with us, as well as your water parameters, if you have them?
This information will go a long way in helping us help you.

tfoster

02-13-2014 02:53 PM

Thanks for the responses!!!

Despite dreading the maintenance I did try to do it at least every two weeks (hence all the filtration). For the last little while I thought I was over a hump or something as the level of agitation did not seem to be as high for the last few months, however if I was able to vacuum and change without too much incident there was a huge sigh of relief.

Needless to say the lady I got the tank from had no idea what was in it, it was her husbands hobby and when he passed away she wanted nothing to do with it. The fish were a bit smaller than they are now but I was aware of the horrible choices made in stocking the tank, but it was what it was.

I suspect the larger fish is the ID and I cannot fathom why those are sold for hobbyists. I have, for about year tried to find an aquarium store with a display tank that is willing to take the larger shark, but have had no success at all, at least in a reasonable radius for transport from where I live.

I was hoping that the sudden deaths were due to the larger fish freaking out for hours and that there wasn't some other issue that required intervention.

Unfortunately I don't have any water parameter info. Initially after moving the tank in the middle of winter and transferring most of the water with the fish I was testing fairly regularly but after a while I stopped as I never seemed to have any problems until Monday this week.

Thanks again!

BWG

02-13-2014 05:02 PM

I would test now. All the filtration in the world isn't going to help remove nitrates. A 15% bi-weekly water change is nothing, especially with the bioload you have with just that shark alone.

rsskylight04

02-13-2014 05:18 PM

Sounds like a ph crash due to old water/ too small waterchanges , then ammonium/ammonia swing when new water was added. Maybe.

tfoster

02-14-2014 11:51 AM

Thanks for all the responses. I went home last night and did a nitrate test and my water was well within acceptable parameters...less than 20 ppm. The only time I saw it higher was when I moved the tank and the fish to my place. The 15% water change was perhaps a conservative guess, when I looked at the tank yesterday it would likely be closer to 20-25%. Again yesterday the shark seemed overly agitated, it had redecorated the tank again and had fresh scrapes all over its body. The mystery for me is why the sudden deaths of the four other fish? At this point, I'm inclined to go with the suggestion that the shark freaking out for hours on end was likely the cause.

As I've had no other problems with losing fish in this tank ever, I questioned what was new. In the last month I replaced the UV filtration system with one that has an in tank pump. I noticed that this pump was making much more noise than usual. I also remembered when I first set up the tank I put an airstone in that I had to remove because the shark was way too agitated with it. I'm now wondering if the noise and vibration from the internal pump in the UV has further set the shark on edge and the water change and gravel vacuuming was the proverbial straw that broke the camels back. I've unplugged the filter and will watch the tank closely.